The long term goal is to replace radioactive tracer methods with C-13 magnetic resonance spectroscopy for metabolic imaging and studies of intermediary metabolism in humans. The immediate goal of the study is to measure hepatic gluconeogenesis relative to citric acid cycle flux in humans by C-13 MRS of blood and urine samples. The experiment is designed to test the reasibility of C-13 enriched compounds as metabolic probes of hepatic function. If successful, the current study will be expanded and serve as a control population for future studies in patients with disease processes known to alter hepatic metabolism.